Gluon SceneBuilder 8.1.1 Problems using Include or Import FXML - javafx

Question

I cannot include a simple fxml file into a BorderPane or TabPane.
Details including some sample code are already reported here:
https://bitbucket.org/gluon-oss/scenebuilder/issues/68/various-problems-trying-to-inlcude-an-fxml
I still have a few questions according this topic:
Is there a limitation of containers where you may fx:include into ? (e.g. are TabPanes not allowed??)
Is there some specific thing I had to do inside the included FXML file which I am missing?
Any other hint?
If you experience the same problems - maybe you could vote for the bug, so we increase the chances to get a fix.

Answer 1

By default, when you include one FXML file into another using Scene Builder menu File -> Include -> FXML..., the included file is added under the root, according the following code:
final FXOMObject rootObject = targetDocument.getFxomRoot();
if (rootObject != null) {
final Selection selection = getEditorController().getSelection();
if (selection.isEmpty() || selection.isSelected(rootObject)) {
targetObject = rootObject;
} else {
targetObject = selection.getAncestor();
}
...
}
In the case of your AnchorWithTabPane.fxml file, if you don't select anything, it will be included under the root:
<AnchorPane ...>
<children>
<TabPane .../>
<fx:include source="UserControl.fxml" />
</children>
</AnchorPane>
Now, if you select TabPane, going through the else condition, it will go again under the root, giving that the tabPane's ancestor is the root itself.
If you select Tab, the ancestor is TabPane, but there you can't include a FXML node.
If you select the AnchorPane of a tab, the ancestor is the tab, and you can't include there a FXML node either.
So the solution or workaround in this case is adding some inner container or node to that anchor pane, and then selecting it: since its ancestor will be the AnchorPane, it will add the FXML node there.
And finally you can delete that temporary container/node.
As a result, you will have:
<TabPane ...>
<tabs>
<Tab text="Untitled Tab 1">
<content>
<AnchorPane ...>
<children>
<fx:include source="UserControl.fxml" />
</children>
</AnchorPane>
</content>
</Tab>
<Tab text="Untitled Tab 2">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0" />
</content>
</Tab>
</tabs>
Regarding your question about what containers can hold an fx:include, all the panes under javafx.scene.layout.* can hold them.
As hint, if you use NetBeans, edit an fxml file, and within the container tags click Ctrl+space, it will show you if the fx:include node is allowed: